Patients with CAH between the ages of 10 and 40 years who are managing well on standard treatment (glucocorticoids, mineralocorticoids) may be eligible for this study. Healthy volunteers that match the enrolled patients in age, sex, race and body fat will be recruited as control subjects. All candidates will be screened with a medical history, physical examination and electrocardiogram (EKG). Body fat will be measured using an instrument called a Bod Pod. The body fat measurement has two parts: first, the subject sits quietly in a large egg-shaped capsule for about 2 to 3 minutes; then the subject breathes into a plastic tube for one minute, followed by three quick panting breaths. Women will have a urine pregnancy test; pregnant women cannot participate in the study.